116 Occurrence of the genus Cryptoceras in Silurian Rocks. 



ration of this latter form, with Endoceras, &c,, from the normal 

 Oi'thoceratites. The external ridges on the siphuncle of Endo- 

 ceras, although so distinctly pointed out by Hall, appear to be 

 forgotten altogether in the descriptions of many European 

 pal?eontologists. Ormoceras, notwithstanding the central posi- 

 tion of its siphuncle, is evidently closely related to Gonioceras, 

 and through that genus, though less closely, to Endoceras. 



If the separation of the Goniatites and Ceratites from the 

 Ammonitidse be disapproved of, they may be placed in that 

 family as separate tribes. Our present object, however, is not 

 to discuss the classification of the chambered Cephalopods, but 

 to point out the occurrence in our Silurian rocks of a type 

 hitherto unannounced, below the Devonian formation. 



In the fifth of the above families, that of the Cyrtoceratidse, 

 characterized by the presence of simple septa, with external or 

 so-called " dorsal" siphuncle, we have three genera : Cyrtoceras, 

 a simply " horned" form, exceedingly abundant ; Gyroceras, a 

 discoidal or "rolled-up" Cyrtoceras, but without contiguous vo- 

 lutions ; and Cryptoceras, likewise a discoidal form, but with con- 

 tiguous whorls. Of the last-named genus, founded by D'Orbigny, 

 but two species appear to have been hitherto recognized, the C. 

 subtuherculatus [Nautilus subtuherculatus) from the Devonian beds 

 of Nassau, and the C. dorsalis [Nautilus dorsalis, Phil.) from the 

 carboniferous limestone of Yorkshire. Quite recently, however, 

 in a specimen from the Black River limestone of Lorette, in 

 Eastern Canada, submitted to us by Mr. Head, the son of His 

 Excellency the Governor-General of Canada, we have remarked 

 the Cryptoceras type of structure, viz. simple septa and an un- 

 mistakeably " dorsal" siphuncle, combined wath a Nautiloidal 

 form of shell. Hall, in the first volume of his ' Palseontology of 

 the State of New York,^ figures and describes, under the name 

 of Lituites undatus, a fossil that may perhaps be identical with 

 the one now under review ; but if so, the generic term "Lituites" 

 should certainly give place to that of " Ci-yjjtoceras." The 

 siphuncle is said to be dorsal', and Professor Hall describes the 

 only examples known to him, as occurring in the Black River 

 limestone of Watertown, in Jefferson County. This same Lituites 

 undatus is quoted by D'Orbigny in his ' Prodrome,^ and also by 

 Pictet in the last edition of his ' Traite de Paleontologie ;' but 

 these palaeontologists appear to ignore completely the dorsal 

 position of the siphuncle as described by Hall. D^Orbigny, in- 

 deed, places it immediately under the following generic defini- 

 tion : " Lituites, Breynius : coquille spirale, a tours contigus, 

 siphon central ;" and this central position of the siphuncle as an 

 essential characteristic of Lituites is also recognized by JM'Coy 

 in his recent work on the British P, Iseozoic Fossils of the Cam- 



